N249, combi valve and secondary air pump

[grayham]

Folks,

My secondary air pump is full of rusty water, and as dead as a dead thing that's been deaded a couple of times to make sure that it's dead. I've found various people who say that the likely cause of this is a faulty combi valve, letting exhaust fumes into the pump, which condense in the pump and bugger it. I've ordered a new combi valve, and am in the process of tracking down a new pump.

My question is this: if I understand things correctly, the N249 controls the combi valve. Supposing the N249 were at fault rather than the combi valve - how would I know? I have no fault codes relating directly to the N249 (just the 'incorrect flow detected' code), but can I be sure that this means that the N249 is OK? I don't want to install a new pump and combi valve only to have the new pump buggered too because I didn't fix the real cause!

Thanks very much.

 

[lc_allan]

Or you could bypass the N249 and remove the whole SAI system and not have to worry about it

 

[Muttley]

N112 controls the combi valve.

 

[grayham]

True, but I'd rather avoid a permanent CEL, and at some point I may want to sell the car, in which case there's a chance that the buyer might take a look and say "Hang on, there's a load of bits missing!".

 

[adam cupra 20vt]

You could just remove the whole SAI system and save yourself a lot of money.

Edit...I didn't see the above reply!

 

[grayham]

N112 controls the combi valve.

Ah! Oops - I guess I meant N112 then... I'm rather new at all this I'm afraid. Far too many things beginning with 'N' for my little brain to hold at once.

 

[Muttley]

I'm pretty sure the Nxxx components are electro-pneumatic switches in VAG-speak, like Gxxx are sensors, Fxxx are switches and Sxxx fuses. Sadly the Sxxx number bears no relation to the fuses position in the fusebox.

The suggested failure mode is that the combi valve jams open through carbon build-up, and the water comes from the exhaust gas. This seems more likely than the N112 failing, as it would have to fail active in order to keep the vacuum supply going to the combi valve, which is normally shut.

 

[Phillc]

True, but I'd rather avoid a permanent CEL, and at some point I may want to sell the car, in which case there's a chance that the buyer might take a look and say "Hang on, there's a load of bits missing!".

As long as you put resistors across the connectors you wont get a permanent light.

 

[grayham]

As long as you put resistors across the connectors you wont get a permanent light.

I've read conflicting claims about that - some say that the "Incorrect flow detected" code will remain. Is there a guaranteed way to permanently get rid of that one?

 

[adam cupra 20vt]

I done quite a bit of research into this in the last couple of weeks as I was going to remove mine at the weekend.......

Some people just unplug theres and fit no resistor and the light never comes on?? although some people fit resistors and the light does come on but only every 2-3 months and they simpy re set it.......I also read a few people have fitted resistors and the light has never come on.

From what I read everyone seems to have different results


Fortunatly for me I managed to fix mine at the weekend so I left it in place

 

[Dan 1.8t]

my n112 bracket snaped so my n112 droped onto my exhaust manifold and melted, so i tried my mates n112 onto my car and i no hav no boost the car is not dumping anymore, but i looked at the numbers on the n112 and mine had a s on it and my mates hav a f on it is there 2 diff types , im a bit lost and dnt no what to do ?

 

[cuprachrissy]

my n112 bracket snaped so my n112 droped onto my exhaust manifold and melted, so i tried my mates n112 onto my car and i no hav no boost the car is not dumping anymore, but i looked at the numbers on the n112 and mine had a s on it and my mates hav a f on it is there 2 diff types , im a bit lost and dnt no what to do ?

yes that was my car you borrowed them off of dan! does anyone know this as he is lost without boost!!!

 

[grayham]

Thanks all for your help. I have been considering ripping out the SAI system, but have pretty much decided to just bite the bullet and fit a new pump. Can get a new pump for £231 (+VAT), so will probably just do that rather than wait around and hope for a secondhand one to turn up. Bah!

Oh and sorry, can't help with the N112 problem above!

 

[adam cupra 20vt]

There is a SAI pump on ebay I saw it a couple of days ago, think it was £60 and had already had the naff rivets replaced with nuts and bolts so it doesn't come apart and leak

 

[Muttley]

I'd suggest a through check of the combi valve to see it's not jammed open, maybe just needs a cleanup.

 

[RyanWaters]

Can you just purely unbolt it and re connect it up after cleaning? Is there amy procedures you need to do after?

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[Andrewwright]

Can you just purely unbolt it and re connect it up after cleaning? Is there amy procedures you need to do after?

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No procedure to do apart from disconnect battery for 15 mins before work, and reconnect after the job is done. Reason being is the ecu cannot pick up on anything if its disconnected so no light will pop up.
Its the throttle body that needs calibration procedure with vcds.

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